1. Field of the Invention
The present invention relates to a bubble generating device for a water tank, more particularly to a bubble generating device which is capable of intermittently controlling the emission of bubbles in the water tank.
2. Description of the Related Art
Bubble generating devices are commonly installed in a water tank, such as an aquarium tank, for aerating the water received therein so as to increase oxygen content in the water. A conventional bubble generating device includes a bubble emission member disposed in the tank, and an air pump connected fluidly to the bubble emission member for providing pressurized air to the bubble emission member such that bubbles can be emitted from the bubble emission member. However, when the conventional bubble generating device is in use, bubbles are continuously emitted from the bubble emission member while the air pump is activated. The scene created by the continuously emitted bubbles in the water tank is relatively monotonous. It is desirable to provide a bubble generating device that provides a varying waterscape in a water tank to result in an enhanced aesthetic effect.
In co-pending U.S. patent application Ser. No. 09/474,689, the Applicant disclosed a bubble generating device for use with a water tank so as to provide the water tank with a varying waterscape. The bubble generating device disclosed in the aforementioned patent application includes a bubble emission member adapted to be disposed in a water receiving chamber of the water tank and formed with a plurality of bubble emission holes, an air pump for providing pressurized air, air passage means for fluidly communicating the air pump and the bubble emission member to permit flow of the pressurized air from the air pump to the bubble emission member, and a control unit for intermittently controlling air flow through the air passage means so as to intermittently control the amount of bubbles emitted from the bubble emission holes of the bubble emission member.